Sebum, or skin oil, is produced in the sebaceous glands located in the pilosebaceous apparatus of the skin and reaches the skin surface through the duct of the hair follicles. The presence of excessive amounts of sebum on the skin surface often results in an unattractive cosmetic condition commonly known as "oily skin". Sebum also plays an important role in the pathogenesis of ache. Sebaceous gland activity is significantly increased in ache subjects, and individuals with the most severe ache often have the highest sebum secretion rates.
The spreading of sebum on the skin surface is thus an important cosmetic parameter since its distribution on the skin surface can determine the appearance of oiliness or greasiness and can contribute to the severity of ache.
It is advantageous, therefore, to have available means for controlling the distribution of sebum over the surface of human skin, with particular regard to skin characterized by an excessive secretion or presence of sebum upon the surface and to affected skin areas of, for example, ache patients. It is also advantageous to have available a facial care composition which will assist the facial stratum corneum in maintaining their barrier and water retention functions at optimum performance in spite of deleterious interactions which the skin may encounter in washing, work, and recreation.
Many currently marketed facial products do not effectively control the distribution of sebum upon the surface of the skin. Without being limited by theory, it is believed that current leave-on emulsion products undesirably modify the surface properties of the skin, thereby increasing the contact angle of the sebum with the skin and thus preventing its spreading. These products cause the secreted sebum to remain as small discrete droplets upon the skin, thus resulting in oily skin and its attendant problems.
Typically, the problem of oily facial skin has been dealt with by frequent cleansing and the use of astringent preparations. However, such remedies are of questionable efficacy and not always practical, and also have the disadvantage of drying, irritating, and abrading the skin. Additionally, any benefits which may be obtained through cleansing and the use of astringents are only temporary. Once the skin has been cleansed of sebum, the skin begins secreting sebum anew so that the oily skin problem soon returns.
The prior art teaches the incorporation of clays, talcs, silicas, starches, polymers, and other such materials into skin care products for absorbing sebum and controlling oily skin. See U.S. Pat. No. 4,940,578, Yoshihara, T. et al., issued Jul. 10, 1990; U.S. Pat. No. 4,885,109, to Umemoto, I. et al., issued Dec. 5, 1989; U.S. Pat. No. 4,536,399, to Flynn, R. G. et al., issued Aug. 20, 1985; U.S. Pat. No. 4,489,058, to Lay, G. E. et al., issued Dec. 18, 1984; U.S. Pat. No. 4,388,301, to Klein, R. W., issued Jun. 14, 1983; and U.S. Pat. No. 4,000,317, to Merida, W. C. et al., issued Dec. 28, 1976. However, the practicality of incorporating sebum absorbing materials is limited by the sebum absorbing capacity of the material, formulation difficulties, and the negative aesthetic properties which these materials impart to finished products. Also, any oil control benefit which may be obtained is merely temporary.
A longer lasting method of reducing sebum on the skin is through the use of topical or systemic agents believed to provide a sebosuppressive effect. See Karg, G. et al., "Sebosuppression", Cosmetics & Toiletries, vol. 102, pp. 140-146 (April 1987); U.S. Pat. No. 4,593,021, to Hsia, S. L. et al., issued Jun. 3, 1986; U.S. Pat. No. 4,587,235, to Bittler, D. et al., issued May 6, 1986; U.S. Pat. No. 4,529,587, to Green, M. R., issued Jul. 16, 1985; U.S. Pat. No. 4,210,654 to Bauer et al., issued Jul. 1, 1980; and U.S. Pat. No. 4,016,287, to Eberhardt et al., issued Apr. 5, 1977. Without being limited by theory, it is believed that sebosuppressive agents decrease the sebum output of the pilosebaceous ducts of the skin, thereby reducing surface oiliness. However, many sebosuppressive agents are potent drugs having undesirable side effects on diuretic activity, inflammation mediators, blood pressure, hormonal levels, cholesterol synthesis, and other bodily functions. Thus, it may not always be practical, desirable, or even possible to utilize sebosuppressive agents to control oily skin.
The control of sebum spreading via topical formulations which do not contain sebosuppressive agents is described in Australian Patent Application 8,319,558 to Herstein et al., published Apr. 12, 1984. This patent discloses formulations for use on oily skin such as cleansers, shampoos, and anti-ache treatments, which contain -gluconamidopropyl dimethyl 2-hydroxyethyl ammonium chloride. However, these formulations have the undesirable characteristic of increasing the contact angle of sebum with the skin and inhibiting the even spreading and distribution of the sebum.
Furthermore, in addition to the limitations of the prior art discussed above, most currently marketed emulsion products actually contribute to and aggravate oily skin problems. Most emulsion products are oil-in-water or water-in-oil emulsions containing high levels of fats and oils. The high levels of fats and oils in these products give them their characteristic heavy and greasy aesthetics and contribute to oily skin problems. The limited number of products which claim to be free from: fats and oils are usually not emulsion type products, but instead are low viscosity, hydro-alcoholic formulations which are too harsh and astringent for regular or frequent use.
Therefore, it would be highly desirable to develop facial compositions which overcome the disadvantages of the prior art. It would also be highly desirable to provide facial compositions which will assist the facial stratum corneum in maintaining their barrier and water retention functions at optimum performance in spite of deleterious interactions which the skin may encounter in washing, work, and recreation.
Conventional cosmetic cream and lotion compositions as described, for example, in Sagatin, Cosmetics Science and Technology, 2nd Edition, Volume 1, Wiley Interscience (1972) and Encyclopedia of Chemical Technology, Third Edition, Volume 7 are known to provide varying degrees of emolliency, barrier and water-retention (moisturizing) benefits.
Other cosmetic compositions are disclosed in, for example, U.S. Pat. No. 4,837,019 to Georgalas et al., issued Jun. 16, 1989 and also in U.S. Pat. No. 4,863,725 to Decknet et al., issued Sep. 5, 1989, both of which are incorporated by reference herein.
To improve moisturizing benefits water-soluble humectants such as glycerine have been added to cosmetic compositions; however these water-soluble humectants generally significantly increase the tacky feeling. Applicants have found that the use of a specific silicone component along with a specific cationic surfactant component in substantially oil-free aqueous gel-type compositions provides improved oil-control along with significantly improved skin feel and provides a visually appealing product. Further, these compositions, when applied, provide the user with improved make-up application and protection from environmental factors (e.g., irritants such as wind, heat and cold) as well as protection from common household irritants (e.g., cleansers and the like). These substantially oil-free gel-type cosmetic compositions are also particularly useful in warmer climates because they reduce the tack associated with heat and humidity.
The present invention therefore provides substantially oil-free gel-type cosmetic compositions which provide improvements in absorption, residue and skinfeel characteristics without detriment to either short or longer term moisturizing effectiveness or emolliency.
It is therefore an object of the present invention to provide improved facial compositions which provide reduced tack and provide the user a smoother skin feel and which reduce the oily appearance and greasy feel of facial skin and control the distribution of sebum upon the skin surface. It is still another object of the present invention to provide compositions which are aesthetically pleasing and substantially free from fats and oils. It is yet another object of the present invention to provide compositions for controlling sebum distribution without incorporating oil-absorbing materials. It is a further object of the present invention to provide oil-free moisturization to minimize skin regreasing over time. It is still a further object to provide skin care compositions which, when applied, provide improved make-up application as well as improved protection from environmental and common household irritants.
These and other objects of this invention will become apparent in light of the following disclosure.